Health36Neospora caninum and Leptospira serovar serostatus in dairy cattlein OntarioCorresponding AuthorPeregrine, A.S.University of GuelphCollaboratorsMartin, S.W.University of GuelphHopwood, D.A.University of GuelphDuffield, T.F.University of GuelphMcEwen, B.University of GuelphHobson, J.C.University of GuelphHietala, S.K.University of CaliforniaCanadian Veterinary Journal (2006) Vol. 47 p. 467-470.Neosporosis is currently the most common cause of abortion in Ontariodairy cattle. A previous survey of 56 Ontario herds indicated that approximately10% of adult cows were seropositive to Neospora caninum, indicatingthat they were likely infected with the parasite. Within individual herds,from 0 to 68% of cows were seropositive, with a median value of 7%. Workelsewhere has indicated that, overall, the risk of abortion is increased inanimals that are seropositive for N. caninum. Furthermore, research donein France has indicated that exposure of cattle to surface water was associatedwith N. caninum seropositivity. Since horizontal transmission isnot the primary route of N. caninum infection in cattle, we hypothesizedthat the association of N. caninum seropositivity with surface water wasdue to exposure to Leptospira in water, and that infection with this bacteriaincreased the susceptibility of cattle to congenital N. caninum infection. Ifso, cows that are seropositive for N. caninum should also be seropositivefor Leptospira. However, testing of cows from 78 farms in Ontario revealedno such association. Among herds not vaccinated against Leptospira, theproportion of herds with one or more cows seropositive for one of 3 individualspecies (serovars) was 45% (L. hardjo), 42% (L. icterohaemorrhagiae)and 58% (L. pomona).37Efficacy of using an internal teat sealer to prevent newintramammary infections in nonlactating dairy cattleCorresponding AuthorSanford, C.J.Canadian Food Inspection AgencyCollaboratorsKeefe, G.P.Atlantic Veterinary CollegeDohoo, I.R.Atlantic Veterinary CollegeLeslie, K.E.University of GuelphDingwell, R.T.University of GuelphDesCôteaux, L.Université de MontréalBarkema, H.W.University of CalgaryJournal of the American Veterinary Medical Association (2006) Vol. 228 p. 1565-1573.Treatment of all cows at dry-off with a single intramammary dose of antibioticis a practice currently recommended by the National Mastitis Council.A potential adjunct or alternative to this practice has recently becomeavailable. This is an inert (bismuth subnitrate) internal teat sealant (ITS) witha gel-like consistency which is infused into the teat cistern either alone orafter a dose of intramammary antibiotic. This study tested the efficacy ofalternative protocols in 2 groups of cows, based on their intramammaryinfection (IMI) status 14 days before dry-off. Cows in group 1 had no IMI;those in group 2 had an IMI in at least 1 quarter. Quarters in group 1 cowswere infused with either ITS or the antibiotic, cloxacillin. All quarters ingroup 2 cows were treated with cloxacillin; half were also infused with ITS.Milk samples were drawn from all quarters 8 days after calving. For group1 cows, there were no differences in IMI rates between treatments—ITSand cloxacillin were equally effective. In group 2 cows, quarters treatedwith both cloxacillin and ITS had fewer new IMI than those treated withcloxacillin alone.82 Highlights in Canadian Dairy Cattle Research - 2007
Health38Prevention of fatty liver in transition dairy cows by subcutaneousinjections of glucagonCorresponding AuthorBeitz, D.C.Iowa State UniversityCollaboratorsNafikov, R.A.Iowa State UniversityAmetaj, B.N.University of AlbertaBobe, G.Iowa State UniversityKoehler, K.J.Iowa State UniversityYoung, J.W.Iowa State UniversityJournal of Dairy Science (2006) Vol. 89 p. 1533-1545.At or around calving, dairy cows are vulnerable to a number of metabolicdisorders, often related to accumulation of fat in the liver. Fatty liver (FL) isthe result of negative energy balance in early lactation—the energy demandfor milk production exceeds the animal’s ability to consume energy-yieldingnutrients. To satisfy energy demand, non-esterified fatty acids(NEFA) are mobilized from adipose (fat) tissues and are taken up by the liverwhere they may be oxidized, stored or exported. When storage exceedsoxidation or export, FL develops and ketosis may ensue. Glucagon is a proteinhormone that promotes an increase in blood glucose by increasingboth the rate of glycogen breakdown and the rate of glucose synthesis inthe liver. Previous work by these authors demonstrated that continuous14-day intravenous infusion of glucagon could be used to treat fatty liverin early lactation cows. The objective of the present trial was to determineif subcutaneous injections of glucagon could prevent FL. Cows were fedhigh energy diets in the last month of the dry period to increase their fatstores. At calving, they were assigned to one of 3 treatments: 7.5 mg/dayof glucagon in saline, 15 mg/day of glucagon in saline or saline alone (control).Injections were administered 3 times per day for 14 days starting at2 days after calving. The 15 mg/day glucagon treatment increased bloodglucose and insulin, decreased blood NEFA and prevented FL. Feed intake,milk production and milk composition were not affected.Health 83
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